The function quartile of the subpackage stats[describe, ...] finds the item in data that corresponds to the quartile specified by which. If the requested quartile falls between entries, it is interpolated.

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The values given by quartile can be thought of as 3 values that partition the data set, once sorted, into 4 data sets of equal weight.

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Half of the difference between the third quartile and the first quartile is a measure of the dispersion of the data. This quantity is known as the semi-interquartile range and the quartile deviation. Refer to describe[standarddeviation] for more information about measures of the dispersion of data.

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Missing data are ignored.

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For information about the parameter gap, see describe[gaps].

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The data must be numeric.

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The command with(stats[describe],quartile) allows the use of the abbreviated form of this command.